Such a control apparatus is known, for example, from DE 43 32 499 A1.
The configuration of the control apparatus described in this publication makes it possible, in a simple way, to store programs and data in a programmable memory unit provided within the control apparatus. These programs and data are prepared by an external source (programming apparatus in the form of a PC and the like). The programmable memory unit is assigned to a first control unit (microprocessor, microcontroller and the like) and functions to store programs and data for the first control unit. Stated more precisely, the measures for the programming (especially when a so-called flash EPROM or the like is used as a memory unit) are limited essentially so that the external source is connected via an interface line (via an interface cable) or the like electrically to the terminal on the control apparatus provided therefor.
A configuration of this kind therefore makes possible a first time programming or reprogramming of the memory unit even in the built-in state of the control apparatus at any time and in a relatively simple manner.
The situation becomes more complicated, however, when one or several further memory units of a control unit or of several additional control units are to be programmed within the control apparatus.
The provision of several control units can, inter alia, be required because the function of a first control unit (main computer) should be monitored by a second control unit (second or safety computer).
In a corresponding application of the teaching disclosed in the above-mentioned DE 43 32 499 A1, an interface, which is accessible for the connection of external programming apparatus, could be provided in such a case for each control unit. This, in turn, would however make the first-time programming of the control apparatus (such as the programming at the end of an assembly line in a motor vehicle manufacturing facility) as well as also the later reprogramming of the control apparatus (for subsequent error removal or corresponding individual customer desires) considerably more complicated and more susceptible to malfunction.